import { Geometry } from "../Geometry.ts";

/** Flat rectangular grid on the XY plane (z=0). */
export class PlaneGeometry extends Geometry {
	constructor(width = 1, height = 1, widthSegments = 1, heightSegments = 1) {
		super();

		this.type = "PlaneGeometry";
		this.parameters = { width, height, widthSegments, heightSegments };

		const gridX = Math.floor(widthSegments);
		const gridY = Math.floor(heightSegments);
		const gridX1 = gridX + 1;
		const gridY1 = gridY + 1;
		const segW = width / gridX;
		const segH = height / gridY;
		const halfW = width / 2;
		const halfH = height / 2;

		const positions = new Float32Array(gridX1 * gridY1 * 3);
		const normals = new Float32Array(gridX1 * gridY1 * 3);
		const uvs = new Float32Array(gridX1 * gridY1 * 2);

		let vi = 0;
		let ni = 0;
		let ui = 0;

		for (let iy = 0; iy < gridY1; iy++) {
			const y = iy * segH - halfH;
			for (let ix = 0; ix < gridX1; ix++) {
				const x = ix * segW - halfW;
				positions[vi++] = x;
				positions[vi++] = y;
				positions[vi++] = 0;
				normals[ni++] = 0;
				normals[ni++] = 0;
				normals[ni++] = 1;
				uvs[ui++] = ix / gridX;
				uvs[ui++] = 1 - iy / gridY;
			}
		}

		const indexCount = gridX * gridY * 6;
		const IndexArray = gridX1 * gridY1 > 65535 ? Uint32Array : Uint16Array;
		const indices = new IndexArray(indexCount);
		let ii = 0;

		for (let iy = 0; iy < gridY; iy++) {
			for (let ix = 0; ix < gridX; ix++) {
				const a = ix + gridX1 * iy;
				const b = ix + gridX1 * (iy + 1);
				const c = ix + 1 + gridX1 * (iy + 1);
				const d = ix + 1 + gridX1 * iy;
				indices[ii++] = a;
				indices[ii++] = d;
				indices[ii++] = b;
				indices[ii++] = b;
				indices[ii++] = d;
				indices[ii++] = c;
			}
		}

		this.setPositions(positions);
		this.setNormals(normals);
		this.setUVs(uvs);
		this.setIndex(indices);
	}
}